High frequency waveguides are commonly made from brass split blocks using conventional machining. This gives rise to several problems. For example, waveguides for higher frequencies require extremely small features and precise dimensional control. For example, a 670 Ghz waveguide (WR 1.5) requires a 191 μm waveguide width and corresponding depth. Conventional machining processes are typically not precise enough for such high frequency waveguides. Additionally, production of these waveguides is a slow and expensive process, and the resulting waveguides cannot be easily integrated into arrays. Furthermore, as waveguides get smaller and begin operating at frequencies approaching the terahertz (THz) range, the placement of integrated circuitry such as control circuits with E-Plane probes must become increasingly precise; up to micron accuracy may be required.
The Jet Propulsion Laboratory (JPL) of the National Aeronautics and Space Administration (NASA) has made waveguides with chip recesses out of brass using conventional machining. These waveguides suffer from problems similar to those mentioned above. The precision with which an integrated circuit can be placed within such a waveguide is largely dependent on the precision of the machine used. Such commonly used machines are generally not capable of the necessary precision discussed above.
The above processes used to fabricate waveguides require multiple steps, which translates into increased cost, lost time and decreased productivity. These waveguide fabrication methods also do not address the issue of providing the precision needed to install integrated circuitry into a waveguide with exceedingly small features within micron accuracy.